بهبود استحکام باند در مواد مرکب ترموپلاستیک پارچه هیبریدی-نخ برای برنامه های کاربردی فن آوری پیشرفته توسط اشعه لیزر

This article examines the development of a laser pretreatment method for glass fibre reinforced polypropylene surfaces for industrial applications. This work aims to create a reproducible surface for bonding low-energy polypropylene which adheres very poorly to most adhesives and forms to the matrix material for plastic composites. The combination of glass fibres with polypropylene in the form of hybrid yarns is intended to produce a low-cost and powerful engineered fibre composite with applications in high-technology industries. The key process is bonding the engineered fibre composite without modifying the material properties. This is done by adhesive bonding. For this purpose, various pretreatment processes were examined and compared, for example, surface degreasing, plasma pretreatment for final cleaning and activation, the use of peel ply and laser pretreatment. The laser pretreatment serves two purposes: the defined generation of different surface structures and the exposure of glass fibres to be able to exploit the adhesive properties of glass surfaces. Moreover, two processes of artificial aging were performed to simulate potential boundary conditions during future use thus ensuring well-founded assessment of the pretreatments. Possible maximum initial adhesive strength is not the only key factor in favour of a decision to use adhesive bonding. Rather is the resistance to aging in real ambient conditions relevant for the long-term usage and stable bonding behaviour. Finally, the surface pretreatment methods are compared with each other, assessed and critical issues of surface pretreatment and material are validated.

At present, due to stricter requirements in many high-technology industries it has become imperative to use lightweight construction materials, such as engineered fibre composites in automobile and aerospace engineering. Modified or even new joining techniques are required when these new materials are used and optimum performance is a key consideration. The Collaborative Research Centre SFB 639 ‘Textile-reinforced composite components for function-integrating multi-material design in complex lightweight applications' examine relevant material joints. These adhesive bonding tests were performed with engineered fibre composites that were manufactured from a hybrid yarn structure that consists of glass and polypropylene fibres. The main aim is to create a reproducible and high-strength adhesive bond of the hybrid-yarn textile thermoplastic composite (HYTT) with like and unlike joining elements. For this purpose it is necessary to improve the bonding properties of polypropylene, which is not unexpected due to its low-energy surface [1], [2], [3], [4], [5], [6], [7], [8] and [9]. Several approaches to increase the adherence have been considered. The potentially feasible alternatives include the pretreatment of the HYTT to ensure optimisation of adhesion between the polypropylene surface and the adhesive [1], [2], [3], [4], [5], [8], [9], [10], [11] and [12]. Another method is the application of a prime coating to the joining area, to improve adhesion of the adhesive agent [1]. Another feasible approach is the modification of polypropylene in terms of the joining technology adhesive bonding or the modification of the adhesive to improve adhesion [1], [6], [13], [14] and [15]. The research done and explained below focuses on the pretreatment of the joining partners to ensure the necessary preconditions and properties for the joining method adhesive bonding. Conventional pretreatment methods, such as peel ply, atmospheric-pressure plasma (AP plasma) and flame impingement for low-energy plastics of low adhesive strength have become noticeable on the market [1], [7], [10] and [16]. For a couple of years, researchers have also been studying alternative laser procedures [1] and [17], thereby focussing in particular on the excimer laser with its high-energy UV radiation [8], [18], [19], [20] and [21]. Two different goals are linked to the examined laser pretreatment. One goal is the selective modification of the topography in the joining area to enlarge the bonding area and to provide for mechanical anchoring of the adhesive. On the other hand, it is necessary that the glass fibres of the HYTT are exposed to be able to exploit the thus improved bonding properties of the glass fibres.